Wobble pump comprising a wobble plate

Abstract

The present invention relates to a barrel-type piston pump ( 1 ) with a swash plate ( 7 ) where the angle of inclination of rotary plate ( 2 ) relative to drive shaft ( 5 ) is adjustable by means of a finger joint ( 8 ).

The invention claimed is: 
     
       1. A barrel-type piston pump comprising a casing and comprising within the casing:
 a drive shaft, 
 a rotary plate driven by the drive shaft, 
 a swash plate caused to oscillate by the rotary plate, and the swash plate being pivotably connected about the axis of the rotary plate relative to the rotary plate, 
 a cylinder block comprising at least two circumferentially distributed compression chambers, and 
 at least two pistons in translation respectively in the compression chambers of the cylinder block, the pistons being driven by the swash plate by connecting rods, 
 
       wherein the rotary plate is driven by the drive shaft by a finger joint, the position of the finger joint determining the inclination of the rotary plate and of the swash plate relative to the drive shaft, and 
       the rotary plate comprises a groove in which a finger of the finger joint moves, the groove being substantially parallel to the axis of the drive shaft. 
     
     
       2. The pump as claimed in  claim 1 , wherein the pump further comprises a return rod, the return rod being in ball jointed connection with the casing and the swash plate. 
     
     
       3. The pump as claimed in  claim 1 , wherein the angle of inclination of the rotary plate and of the swash plate relative to the axis of the drive shaft ranges between 70° and 90°. 
     
     
       4. The pump as claimed in  claim 1 , wherein the pump comprises means for controlling the inclination of the rotary plate relative to the drive shaft. 
     
     
       5. The pump as claimed in  claim 4 , wherein the energy of the control means comes from a source external to the pump. 
     
     
       6. The pump as claimed in  claim 5 , wherein the source external to the pump comprises a fluid under pressure. 
     
     
       7. The pump as claimed in  claim 4 , wherein the energy of the control means is taken from the drive shaft. 
     
     
       8. The pump as claimed in  claim 1 , wherein the cylinder block is stationary relative to the casing. 
     
     
       9. A method for carrying out a drilling operation, comprising injecting drilling mud into a wellbore using the barrel-type piston pump as claimed in  claim 1 . 
     
     
       10. A barrel-type piston pump comprising:
 a drive shaft, 
 a rotary plate, 
 a swash plate pivotably connected about the axis of the rotary plate, 
 a finger joint connecting the drive shaft to the rotary plate, the position of the finger joint determining the inclination of the rotary plate and the swash plate relative to the drive shaft, the rotary plate comprising a groove in which a finger of the finger joint moves, the groove being substantially parallel to the axis of the drive shaft, 
 a cylinder block comprising two compression chambers, 
 pistons in the compression chambers, and 
 connecting rods between the swash plate and the pistons. 
 
     
     
       11. The pump as claimed in  claim 10 , wherein the pump comprises a casing and a return rod, and the return rod is in ball jointed connection with the casing and the swash plate. 
     
     
       12. The pump as claimed in  claim 10 , wherein the angle of inclination of the rotary plate and of the swash plate relative to the axis of the drive shaft ranges between 70° and 90°. 
     
     
       13. A method for carrying out a drilling operation, comprising injecting drilling mud into a wellbore using the barrel-type piston pump as claimed in  claim 10 .